Importance of inlet boundary conditions for numerical simulation of combustor flows

The validity of flowfield predictions resulting from the choice of inlet velocity profiles is assessed. Results demonstrate that realistic predictions are forthcoming only from the inclusion of realistic axial, radial, and swirl velocity profile as inlet conditions. The ensuing flowfields are characterized by means of velocity profile and streamline patterns, and illustrate the large-scale effects of inlet swirl and velocity profiles on flowfields. Clearly, measured inlet profiles must be used in future turbulence modeling development studies for improved simulation of flowfields.

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“…3. Sturgess et al 15 gave predictions of several sample cases to illustrate the importance of inlet boundary conditions in prediction studies.…”

Section: A Idealized Velocity Profilesmentioning

confidence: 99%

Inlet velocity profile effects on turbulent swirling flow predictions

Dong

Lilley

1994

Journal of Propulsion and Power

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“…an important factor since when ln(Rlellilig these types of flows it. is known that the l)onn(Liry co11(litions exert an important influence, [25,26]. The radial velocity di lrs cfltite rapidly and is near zero for x/D >_0.411.…”

Section: Experimental Results and Dis-cussionmentioning

confidence: 99%

Three Component LDV Velocity Measurements in a Can Type Research Combustor for CFD Validation: Part 1 — Isothermal

Ahmed¹,

Rose

Nejad³

1992

Volume 3: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations

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A two-c•oinpolleiit fibre optic LDV system has 1,c , c•11 employed to pleasure three llleall velocity colll ,uiiellts and five Revllulcls Stress cullll>lnlcllts ill it cullfined, isotllernial strollglyy swirling flowfiel(1. The prim ry ol)jectivl• is to provide complete 1)ellclllllerhilellt mill it tVl,ic•rtl I,• -F itiotll•1. Measurements slit )\V the radial vebsity (01111)1 il('ilt (close to the swiller exit) to he of the sal ie magiiitucl.e its the axial and swirl collipollellts. Velocity measurements obtained close to the cu1111mstur wall slloulcl be treated with1 carttiull as these were must affected it signal lluise as it result of illterllal wall rc•.fiections. NOMENCLATURE 1 = l(u + x7 2 + c7 2 ); turbulent kinetic ellergti V =pressure 11, 2', u' = fluctuating velocity c•olllpullellts X, 1', H = axial,radial and azunutlial coordinates U2 , x7 2 , zu 2 = Reyllulcls llurlllustor radius S = swirl llullll )er U. T'. 11 -= lily lll vc•locity collll)ollellts _ axial velocity, illnllecliately upstrealll of swirlce1 = uncertainty in velocity L y) = swirler vane angle o', (J,,, la j^• = standard lleviatioll of 11ieasitrc 1 i1.1li11. radial and swirl velocities length an(l tlierel)u% smaller c•o1111nlstors, (4) improved stal,ility, (5) uniform l,atterll factor (leading to illcreased turbine life) amid (6) imiiproved l,low-off lilllits.Detailed knowledge of confined swirling flows and flames is required for proper clesigli aiitl perftn'mntince control of turbine and ramjet combustors. The majority of the research to elate has the ('(11111111)11 goal of increasing the umiderstallcliiig of such comiiplex llowlields and illlprovillg the acc uracv of the conipu-

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“…The calculated streamline contours (not shown) demonstrate the characteristic hourglass contours arising from entrainment of the secondary air into the lower momentum centerline region. While the predictive accuracy is only moderately satisfactory due to a myriad of inlet boundary condition unknowns (see Sturgess et at, 1986) and turbulence model inadequacies, the calculation does calculate qualitatively the "correct' flow features expected from a stationary state analysis. The LDA data predictions for the reacting flow cases are qualitatively very similar and differ primarily in the magnitude of the velocities in the recovery region (due to volumetric expansion).…”

Section: S Tmentioning

confidence: 96%

Modeling of Local Extinction in Turbulent Flames

Sloan

Sturgess

1994

Volume 3: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations

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The Eddy Dissipation Concept (EDC), proposed by Magnussen (1985), advances the concept that the reactants are homogeneously mixed within the fine eddy structures of turbulence and that the fine structures may therefore be regarded as perfectly stirred reactors (PSRs). To understand more fully the extent to which such a sub-grid scale stirred reactor concept could be applied within the context of a computational fluid dynamics (CFD) calculation to model local or global extinction phenomena: (1) various kinetic mechanisms are investigated with respect to CPU penalty and predictive accuracy in comparisons with stirred reactor lean blowout (LBO) data and (2) a simplified time-scale comparison, extracted from the EDC model and applied locally in a fast-chemistry CFD computation is evaluated with respect to its capabilities to predict attached and lifted flames. Comparisons of kinetic mechanisms with PSR lean blowout data indicate severe discrepancies in the predictions with the data and with each other. Possible explanations are delineated and discussed. Comparisons of the attached and lifted flame predictions with experimental data are presented for some benchscale burner cases. The model is only moderately successful in predicting lifted flames and fails completely in the attached flame case. Possible explanations and research avenues are reviewed and discussed.

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Importance of inlet boundary conditions for numerical simulation of combustor flows

Abstract: To validate computer codes for mathematical simu

Cited by 19 publications

References 2 publications

Inlet velocity profile effects on turbulent swirling flow predictions

Inlet velocity profile effects on turbulent swirling flow predictions

Three Component LDV Velocity Measurements in a Can Type Research Combustor for CFD Validation: Part 1 — Isothermal

Modeling of Local Extinction in Turbulent Flames

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